Single channel high resolution television systems, called or known as receiver interchange systems, have been proposed by means of the Massachusetts Institute of Technology (MIT) of the U.S.A. This is a system in which the vertical dimension of the displayed picture image or signal is reduced in accordance with the NTSC system and the signals for improving the resolution of the displayed picture image or signal are incorporated within empty sites defined within the upper and lower sections of the screen. (See the journal "Spectrum"; No 11, pp. 20-25, November 1988; Maruzen & Co.)
Attempts have also been made to improve the resolution of the displayed picture image or signal as viewed in the vertical direction of a television screen normally having an aspect ratio of 3:4. For this purpose, scanning lines for increasing the resolution of the displayed picture image or signal are developed in an amount which corresponds to the predetermined scanning lines comprising the original scanning lines of the picture. The difference between the signals of the scanning lines for the upper and lower sections of the pictures are therefore accommodated or reconciled, and the number of scanning lines which are visible to the human eye is doubled.
The applicant of the present invention has also proposed a television system characterized by means of improved resolution (Japanese Provisional Patent Applications 63-266848 and 2-113688). According to this system, the signals for improving the resolution of the picture images or signals in the vertical and horizontal directions are inserted into the no-picture portions of the signals as described above upon the transmitting side. On the receiving side, a circuit for detecting the movement of interlace signals is provided, and the resolution in the vertical direction is increased by utilizing the information upon the front field.
It appears that the basic concept of the system proposed by means of MIT is to increase the resolution of the picture image or signal in the vertical direction and it does not expect or encompass an increase in the resolution of the picture image or signal in the horizontal direction. As a result, resolution of the picture is not improved very much.
Similarly, the attempt to improve the resolution of the displayed picture image or signal by means of the use of an additional number of scanning lines which corresponds to the original number of scanning lines will not be successful because it is difficult to transmit all of the predetermined number of scanning lines even when special transmission apparatus is provided or special transmission techniques are employed upon the transmitting side so as not to transmit picture signals in the cinemascope mode and consequently, an excessive number of scanning lines are nevertheless transmitted. Furthermore, even when such image transmission and reception is successful, the resolution of the displayed picture image or signal will be improved only in the vertical direction.
According to the technique which the applicant of the present invention has previously proposed, the compensation components in the horizontal and vertical directions are simultaneously transmitted to the no-picture portions defined within the upper and lower sections of the raster for use upon a cinemascope screen. At the receiving side, the signals transmitted onto the no-picture portions of the above raster are restored and added to the signals transmitted onto the oblong screen portion defined at the center of the raster in order to obtain a picture image having a high degree of resolution.
However, because the reproduced picture image or signal displayed upon the oblong screen at the center of raster has the same interlace signals as that of the NTSC, the transmission signal of the television system is the same. Thus, the resolution of the moving picture portion of the picture image or signal in the vertical direction is 1/2 that of the still picture portion of the picture image or signal. In contrast to such picture signals, it is desired in accordance with the technique previously proposed to restore and add the resolution compensation signals, which are transmitted to the no-picture portions of the raster. Because the resolution of the basic picture signal is extensively decreased during movement thereof, it has become meaningless to introduce or utilize resolution compensation techniques as previously accomplished in connection with the moving portions of the picture image or signal. The desired effect is nevertheless able to be obtained in connection with the still picture portion.